How to Fertilize Your Lawn

Learn how to fertilize your lawn to make it lush and thick. Get tips on testing your soil to find out what it needs: seed, fertilizer or lime. Learn how to spread those materials and find out when you should water your lawn.

LESLIE: Are you green with envy over your neighbor’s lush lawn? Well, that lawn, it did not happen to look that way just by magic.

TOM: That’s right. It takes work to maintain a lawn[1] and one of the necessary steps is fertilizing. You’ve got to get that just right if you want your lawn to look great. Landscaping contractor Roger Cook, from TV’s This Old House, is here to help you make your lawn the envy of your block.

Welcome, Roger.

ROGER: Thank you.

TOM: Now, this is something that I think we’re all set up for disappointment, because we all see the local golf courses and the neighbors on the street that have golf course-like lawns but never can quite get it right ourselves. It’s a pretty complicated process to get it – when you think about all the things you’re battling. I mean you’re battling weather, you’re battling the seed that you choose, you’re battling the fertilizer, you’re battling the weeds. How do you win that battle?

ROGER: You don’t. You work the little battles; you win the little, tiny wars.

TOM: So you choose the ones you can win.

ROGER: Exactly. You can’t change the soil underneath the lawn, so you have to deal with what you have and work with that.

LESLIE: So what are some of the things you need to sort of arm yourself with, knowledge-wise, so that you can head to the home center to make those right decisions?

ROGER: Well, the first thing I would tell you to do is get a soil test[2] done. That’s going to tell you exactly what’s going in the soil, whether it needs nitrogen, phosphorus or it needs lime to balance it and change the pH. Without that, you’re just going blind and putting things down on the lawn.

TOM: And once you do know that your soil is in good shape and let’s say you do need to add some things to it, are there some tools that actually make that easier? Because lawns are just so big. I mean let’s face it: it’s a lot of work to get it spread just evenly, not to put too much or too little in one particular area. How do you kind of eliminate the human-failure factor when you’re trying to add fertilizer or lime or seed?

ROGER: The first thing you have to do is read the directions on the bag, then read the directions on your spreader.

TOM: Guys hate to do that.

ROGER: Well, you’ve got to, in this case. There’s a number on the bag that will correspond to the spreader you’re using to put down the product at just the right rate. You don’t want to put down too little and you don’t want to do too much.

Couple things to be careful of. If you put down too much fertilizer – say you stop and it comes pouring out – it’s going to kill the lawn. Number two, if you use a drop spreader, you have to be very careful because there’s no overlap. I can’t tell you how many lawns I’ve seen where after using a drop spreader, there’s stripes all up and down the front lawn. And that’s not a good thing.

LESLIE: Now, is there a better time of year, over others, to add this variety of components, like the fertilizer, like the lime, like the cedar? Do you do it all at once in, say, the spring?

ROGER: The lawn needs to be fed consistently over the season.

LESLIE: OK.

ROGER: Usually, it’s three or four feedings is what I recommend to people. In the spring, you’re going to get a lot of growth out of your lawn. So if you add a fertilizer[3] which has a lot of nitrogen, which is the first number, then you’re going to get 4 to 6 inches of growth a week and you don’t need that; that makes it hard to cut.

So in the spring, I like to lower the nitrogen a little bit. Because in the spring, 75 percent of that nitrogen goes to leaves, not to the roots. In the fall, when you put on a late-fall application, 75 percent of that nitrogen goes to the roots instead of pushing top-growth. So in the …

LESLIE: And that’s just based on the thickness of the lawn at that point? Or is there a different fertilizer that you’re using?

ROGER: No, it’s based on the physiology of the plant. The plant is getting ready for winter, so it wants to store a lot of energy so the following spring it’ll just pop up.

LESLIE: OK.

TOM: Now, you mentioned cutting. I think a lot of folks tend to want to cut their grass very, very low but that can actually hurt the grass, can’t it?

ROGER: That’s the worst thing you can do for a lawn. Especially if it’s grown long, you haven’t cut it in a week or two, you can even burn the lawn.

But the thing about a long blade of grass is it actually shades the ground below and keeping it cool, keeping it moist. But more importantly, that helps stop weed seeds from germinating.

TOM: Right. So if you think you’re doing yourself a favor by cutting it low, you’re actually making more work, because you’re going to get more weeds and the grass that does come out is not going to be nearly as healthy.

ROGER: Right. And if you scalp an area, that’s killing the grass and the weeds will just climb right in there.

TOM: Now, what about watering when it comes to the fertilizing and the feeding cycle? Do you always water after that?

ROGER: I like to water to just to get the material down into the ground, so it won’t break down from the sun’s rays, and just get it down to the roots, which is where you need it to be.

TOM: Great advice. Roger Cook from TV’s This Old House, I think our lawns are going to be looking a lot healthier thanks to your advice.

ROGER: The neighbors will be green with envy.

LESLIE: Alright. You can catch the current season of This Old House and Ask This Old House on PBS. For your local listings and a step-by-step video on how you can fertilizer your lawn and some other projects, visit ThisOldHouse.com.

TOM: And This Old House and Ask This Old House are brought to you by The Home Depot. The Home Depot, more saving, more doing.